Firmware verification for small and medium industries is a challenging task; as a matter of fact, they generally do not have personnel dedicated to such activity. In this context, verification is executed very late in the design flow, and it is usually carried on by the same engineers involved in coding and testing. The specifications initially discussed with the customers are generally not formalised, leading to ambiguity in the expected functionalities. The adoption of a more formal design flow would require the recruitment of people with expertise in formal and semi-formal verification, which is not often compatible with the budget resources of small and medium industries. The alternative is helping the existing engineers with tools and methodologies they can easily adopt without being experts in formal methods.The paper follows this direction by presenting MIST, a framework for the automatic generation of an assertion-based verification environment and its integrated execution inside an off-the-shelf industrial design tool. In particular, MIST allows generating a complete environment to verify C/C++ firmware starting from informal specifications.Given a set of specifications written in natural language, the tool guides the user in translating each specification into an XML formal description, capturing a temporal behaviour that must hold in the design. Our XML format guarantees the same expressiveness of linear temporal logic, but it is designed to be used by designers that are not familiar with formal methods. Once each behaviour is formalised, MIST automatically generates the corresponding testbench and checker to stimulate and verify the design. To guide the verification process, MIST employs a clustering procedure that classifies the internal states of the firmware. Such classification aims at finding an effective ordering to check the expected behaviours and to advise for possible specification holes.MIST has been fully integrated into the IAR System EmbeddedWorkbench. Its effectiveness and efficiency have been evaluated to formalise and check a complex test plan for industrial firmware.